<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>侦听器</title>
    <script src="./vue.js"></script>
    <script src="./axios.min.js"></script>
    <script src="./lodash.min.js"></script>
</head>
<body>
    <div id="app">
        <p>
            Ask a yes/no question:
            <input type="text" v-model="question">
        </p>
        <p>{{ answer }}</p>
    </div>
</body>
<script>
    var vm = new Vue({
        el: '#app',
        data: {
            question: '',
            answer: 'I cannot give you an answer until you ask a question'
        },
        watch: {
            // 如果 'question' 发生改变，这个函数就会运行
            question: function(newQuestion,oldQuestion){
                console.log(oldQuestion+'....')
                console.log(newQuestion+'....')
                this.answer = 'Waiting for you to stop typing...'
                this.debouncedGetAnswer()
            }
        },
        created: function(){
            // '_.debounce' 是一个通过 Lodash限制操作频率的函数。
            // 在这个例子中，我们希望限制王文yesno.wtf/api 的频率
            // AJAX 请求直到用户输入完毕才会发出。
            this.debouncedGetAnswer = _.debounce(this.getAnswer,500)
        },
        methods: {
            getAnswer: function(){
                if(this.question.indexOf('?') === -1) {
                    this.answer = 'Questions usually contain a question mark. ;-)'
                    return
                }
                this.answer = 'Thinking'
                var vm = this
                axios.get('https://yesno.wtf/api')
                .then(function (response) {
                    vm.answer = _.capitalize(response.data.answer)
                })
                .catch(function(error){
                    vm.answer = 'Error! Could not reach the API. ' + error
                })
            }
        }
    })
</script>
</html>